The present invention relates generally to an electronic interconnect packaging technology. More specifically, the present invention relates to a coplanar waveguide launch package technology.
As illustrated in FIG. 1 (in a perspective view), for various purposes such as testing and measurements, high frequency electronic signals carried on a coaxial transmission line 10 need to be coupled to a coplanar waveguide 20. The transmission line 10 type is often referred to as “coaxial transmission line” or “coax” for short, and the signal is voltage on a center conductor wire 12 relative to an outer ground shield 13. The coplanar waveguide 20 typically includes a signal trace 22 and ground traces 24 separated from the signal trace 22, both fabricated on an insulating substrate 26.
The coax 10 and the coplanar waveguide 20 are not connected directly. Rather, the signal coupling from the coax 10 to coplanar waveguide 20 is accomplished using a coplanar waveguide package 30 as illustrated in FIGS. 2A and 2B. For frequencies above 10 GHz, as illustrated in FIG. 2A (in a perspective view), the coplanar waveguide package 30 is typically machined from its top-side to the mounting flanges 36 and from its bottom-side (or under-side) to the mounting flanges 36 resulting in a top-side cavity 32 and a bottom-side cavity 34. The coplanar waveguide 20 is attached to the flanges 36, in the bottom-side cavity 34, to the coplanar waveguide package 30 with solder or conductive adhesive allowing the ground traces 24 to make electrical contact with the coplanar waveguide package 30.
The coax 10 connects to the coplanar waveguide launch package 30 via a connector (not shown in the perspective drawing of FIG. 2A. The signal is transferred from the center conductor wire 12 of FIG. 1 to a pin 15 (illustrated in FIG. 2B), the pin 15 terminating at a launch 38 and meeting the signal trace 22 at the launch 38. The launch 38 generally refers to the area of the coplanar waveguide package 30 where the pin 15 contacts the signal trace 22. The launch 38 is illustrated in more detail, in FIG. 2B. The ground shield 13 of the coax 10 is electrically connected to the coplanar waveguide package, the pin 15 being insulated from the coplanar waveguide package 30. Thus, the coplanar waveguide package 30 is the “ground” relative to the pin 15 and the signal trace 22 of the coplanar waveguide 20.
In order to minimize signal reflections at the launch 38, the pin 15 and the signal trace 22 need be precisely aligned in all three dimensions. For this reason, the top-side cavity 32 and the bottom-side cavity 34 must be machined very precisely relative to each other. This is difficult to achieve leading to relatively high cost of manufacture of the coplanar waveguide package 30. Further, the removal of much material of the coplanar waveguide package 30 to create the bottom-side cavity 34 leaves little material to support mounting of components on the coplanar waveguide package 30. Finally, the coplanar waveguide package 30 needs a bottom-lid (not shown) to enclose the bottom-side cavity 34 for environmental and electrical shielding of the bottom-side of the coplanar waveguide package 30. The lid requirement adds to the cost of the manufacture of the coplanar waveguide package 30.
Consequently, there remains a need for better coplanar techniques and devices to minimize power consumption while providing sufficient responses to users.